The dynamo model of solar magnetic field generation assumes
that magnetic flux is retained at the dynamo site for times
of the order of the solar-cycle period. However, flux tubes
in the solar convection zone are expected to be buoyant,
rising to the surface on timescales much shorter than the
solar cycle. Since the initial 1955 paper by Parker on this
puzzle, there have been numerous investigations into the
detailed physics of buoyant flux tubes, but no definitive
conclusions have yet been reached.

We investigate the role of thermal conduction in flux tube
dynamics using MHD simulations. We expect that the thermal
conductivity can vary with conditions inside the tube
relative to those in the ambient fluid and that such
variation in turn affects the tube's energetics and
evolution. Preliminary results suggest that suppressed
thermal conductivity inside the tube can significantly
affect tube morphology and evolution, depending on the
characteristics of the tube and its surroundings. We discuss
possible implications of our results for solar surface
magnetic fields.

D.D.L. acknowledges support from an NSF-NATO Postdoctoral
Fellowship in Science and Engineering. We thank Thierry
Emonet for helpful discussions. We are grateful to Mark Rast
for the use of his MHD code. The numerical simulations were
performed on the Cray T3E at CIEMAT in Madrid, Spain.

The author(s) of this abstract have provided an email address
for comments about the abstract:
dlenz@ll.iac.es